Originally Printed in the Australian Bee Journal February 2015
With the absence of Varroa, access to quality nutrition and no harsh winters, Australian honey bees are faring quite well compared to their counterparts around the world. We haven’t seen major colony losses and haven’t had to conduct wide-scale investigations into “what’s killing our bees” because, for the most part, our honey bees are doing just fine.
Meanwhile, in the rest of the world, untold amounts of money and time have been invested into understanding the reasons behind the global decline of pollinators. Honey bees seem to get the most attention serving as the poster child for all pollinators, for better or worse. This is partly because humans have been engaged with honey bees for many thousands of years, partly because they are fascinating social insects that are accessible to study and partly because we are reliant on them to pollinate our intensively planted food crops.
Because the European honey bee (Apis mellifera) is not native to many of the geographic regions (including Australia) that it now inhabits there is great controversy within the scientific community including conservationists, agriculturalists/ horticulturalists and apiarists over where honey bees should and shouldn’t live. The argument is that honey bees displace native pollinators because of their adaptability to different environments and climates. Strict conservationists would like to send all honey bees back to Europe or Africa freeing up resources for native wildlife. However, native pollinators aren’t up to the task to pollinate 1000’s of hectares of agricultural crops nor do they make honey. So unfortunately for them, honey bees aren’t being deported any time soon.
In Europe however, Apis mellifera is native with about 10 subspecies represented, so saving the honey bee is not only a matter of pollination security or saving an apicultural industry, but it is fundamentally a matter of conservation. These subspecies were influenced by the last glacial period when the mountain chains of the Pyrenees, the Alps and the Balkans acted as geographic barriers preventing the free movement of honey bee genes. Because of this isolation, populations of honey bees (subspecies) have developed distinct characteristics adapting them to the local climactic and disease pressures.
People around the world understand the important place that honey bees play in our modern life and when faced with global honey bee decline, researchers from 69 countries from across the world joined together forming an organization called COLOSS (Prevention of honey bee COlony LOSSes-www.coloss.org), an “international non-profit focused on improving the well-being of bees at a global level”. In 2009 COLOSS commenced, a 2 year Europe-wide research project with the goal of understanding how pests and diseases impacted locally adapted bees in their own environment and in foreign environments.
Altogether 597 colonies were established in 20 test apiaries spread over 11 countries. The genetic strains (subspecies) belonged to Apis mellifera (from now on A. m.) carnica, A. m. ligustica, A. m. macedonica, A. m. mellifera, A. m. siciliana. At each location, the local strain of bees was tested together with two “foreign” strains starting with a minimum of 10 colonies from each origin. Over half of the queens were from established breeding programs selecting for traditional favorable traits such as high honey yield and gentleness. The others were from conservation programs generally managed by a few beekeepers focusing on subspecies closed to extinction and have not been selected for beekeeper-desired traits.
The climates over the study area differed greatly from the cold north in Finland where bees were cooped up for months at a time to warm Greece where bees were able to fly freely all year.
Over the course of the study, colonies were evaluated for Varroa loads, nosema spp. levels, viruses, swarming tendencies, hygienic behaviour, defensiveness, and population dynamics. No colonies were treated with chemicals to combat diseases or Varroa, however in some apiaries, Varroa was controlled by removing the brood from the colony during the summer. Researchers and technicians at participating institutions gathered for several field days to harmonize their evaluation techniques and used identical methods for the course of the study.
Of the 597 colonies observed, only 94 (15.7%) survived until the end of the study (March 2012). The main cause of loss was Varroa infestations (38.4%), followed by queen problems (16.9%) and nosema (7.3%). Other causes lumped together including weakness, starvation, winter death, robbing, etc. caused 33.8% of colony deaths. Only 3.4% of colony deaths were unknown.
Overall, no particular strain proved to be the best across all environments- said another way- there was no super bee. Interestingly, the locally adapted strains survived longer in each apiary on average compared to the non-local strains but no specific cause of death impacted the non-local strains more than the local strains.
Climactic conditions influence factors such as length of brood season, amount of brood carried and colony bee density. All of which impact Varroa infestation levels and viral loads and have cascading effects for the colony down the track. Not surprisingly, the location of the apiary impacted overall colony mortality providing not only different climactic stressors (cold vs warm winters) but differing pathogen associations and potentially different pathogen strains.
The locally adapted strains of honey bees have evolved survival strategies to deal with all of these pressures in concert. Remove a strain from their environment and they don’t necessarily fare as well. Even colonies from “survivor stock” that exhibit Varroa tolerance on their home turf did not show an overall improved survivorship or resistance to Varroa once they left home.
This research gives much food for thought as it is the first large scale project that acknowledges the positive influence that local adaptation has on colony health.
As beekeepers, we make management decisions to keep our colonies healthy and diseases low. This may mean feeding them sugar or protein or antibiotics or moving them to better forage. We also breed off of bees with desirable traits (good temperament, honey production). This is because we need them to do a job for us- make bees to pollinate plants or to make honey and we want to enjoy working with them. In doing so, we remove many selective pressures and that would otherwise shape their behaviour, disease resistance and synchronization with the local flora in other words- make them independent of us.
Honey bees will never be a domesticated animal; there will always be some bit out of our control, and this is a good thing. Australia is not necessarily an easy place to live as a feral honey bee but is perhaps one of the last places on the planet with a significant feral honey bee population. Localized populations are adapting to their unique environment as you read this article. Marrying the survival capacity of local strains with the traits essential for a thriving beekeeping operation will make great strides in creating a resilient apicultural industry.
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